Fasting in Ramadan, which requires abstaining from food, drink, and sexual intercourse from dawn until sunset, is one of the Five Pillars of Islam. The Prophet (peace and blessings be upon him) said, “Islam is built upon five pillars: testifying that there is no god except Allah and that Muhammad is the Messenger of Allah, performing Prayer, paying the zakah, making the pilgrimage to the Sacred House (Hajj), and fasting the month of Ramadan.” (Reported by Al-Bukhari and Muslim)
It is religiously permissible for one who travels about 85 km (53 mi) or more to break his fast in Ramadan provided that one compensates by fasting other days after Ramadan. Yet, Muslim jurists disagree regarding the time when the Islamic regulations for traveling are applicable. The preferred opinion is that the rules of traveling start when the person goes beyond the location or the area where he lives. So, it is not allowed for him to break the fast within that area because he may be confronted with an unexpected circumstance that forces him to stay.
Responding to this question, Dr. `Abdur-Rahman Al- `Adawi, Professor of Fiqh at Al-Azhar University, states the following:
Almighty Allah says, “… and whosoever of you is sick or on a journey, (let him fast the same) number of other days. Allah desireth for you ease; He desireth not hardship for you; and (He desireth) that ye should complete the period, and that ye should magnify Allah for having guided you, and that peradventure ye may be thankful.” (Al-Baqarah: 185)
In this verse, Almighty Allah makes it lawful for the traveler to break the fast in Ramadan. The Prophet (peace and blessings be upon him) is reported to have said, “Allah has exempted the traveler from the obligation of fasting.”
Consequently, breaking the fast during the month of Ramadan is allowed for the traveler, but if someone finds that he is capable of fasting, fasting would be better, as Hamzah Al-Aslami once asked the Prophet (peace and blessings be upon him), “O Messenger of Allah, I feel able to fast when traveling, will I be sinful (if I fast while traveling)?” The Prophet (peace and blessings be upon him) said: “It is a dispensation from Allah, he who makes use of it does good and he who likes to fast, there is no blame on him.” (Reported by Muslim)
the dispensation for breaking the fast (is the same as that) for shortening the prayer, that is the distance of traveling should be (at least) 85 km (53 mi). Besides, someone is not regarded as a traveler unless he goes beyond the inhabited area of the location where he lives. So, someone who intends to travel but neither starts the journey nor goes beyond his area is not permitted to break the fast. If someone who finds that it is difficult to go on fasting while traveling or that fasting will physiologically harm him, it is better for him to break the fast. Jabir (may Allah be pleased with him) is reported to have said, “Once the Prophet (peace and blessings be upon him) passed by a man lying under a tree while water was being sprayed at his face (because of what he was feeling due to fasting). The Prophet asked, ‘What about this man?’ They said: ‘He is fasting.’ The Prophet (peace and blessings be upon him) said, ‘Fasting is not recommended while traveling.’”
Breaking the fast is better than fasting if the traveler is among the Muslim army. In such a case, fasting is not preferred, especially if it physiologically weakens him so that he may not be able to join the battle.
It is allowed for the person to break the fast either in the daytime or in the middle of the day, as long as he meets the conditions for being a traveler. This is because if traveling starts in the evening and continues till the daytime, it is an excuse for breaking the fast. This is the same as if there is a reason for breaking the fast during the daytime such as illness, which is one of the two stated conditions for breaking the fast, namely, illness and traveling. Just as being affected by illness during the daytime is a reason for a person to break the fast, it is also allowed for him to break the fast in case he is traveling in the daytime. The traveler must fast the same number of days he broke in Ramadan.”